Backside silicon wafer design reducing image artifacts from infrared radiation

Active Publication Date: 2007-02-08
APTINA IMAGING CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0014] The present invention provides imaging devices having reduced image artifacts by significantly reducing or redirecting IR radiation penetrating into the imager substrate and therefore reducing IR con

Problems solved by technology

One problem with image devices are the creation of artifacts.
Penetration of infrared (IR) radiation to the substrate may create artifacts in the image sensors.
Because of the small number of dark pixels used to calculate the reference signal, usually the dark reference signal is calculated from a

Method used

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  • Backside silicon wafer design reducing image artifacts from infrared radiation
  • Backside silicon wafer design reducing image artifacts from infrared radiation
  • Backside silicon wafer design reducing image artifacts from infrared radiation

Examples

Experimental program
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Example

[0047] Reference is now made to FIG. 3 which schematically illustrates a second embodiment of the solid-state imager 20 of the present invention. The illustrated FIG. 3 embodiment comprises a micro-lens array 70 formed over a color filter layer 100 and spacer layer 25, which are formed over a pixel cell array 26 formed in and / or over a first surface of substrate 30, which may be any of the types of substrate described above. The imager 20 further comprises an absorption layer 84 formed on a second surface 32 of the substrate 30. The absorption layer 84 may be formed of any suitable material which absorbs IR radiation at the wavelength of between about 800 to about 1150 nm. Preferably the absorption layer 84 is formed from Ge, SiGe, SiC, or the like. Most preferably, the absorption layer 84 is formed from germanium, as germanium for these purposes can be deposited on the surface of the substrate 30 using standard vacuum deposition techniques. While the absorption layer 84 is illustra...

Example

[0049] Reference is now made to FIG. 4, which schematically illustrates a third embodiment of the solid-state imager 20 of the present invention. The illustrated embodiment comprises an imaging device having a micro-lens array 70 formed over a color filter layer 100 and spacer layer 25, which are formed over a pixel cell array 26 formed in and / or over a first surface of substrate 30. The imager 20 further comprises a roughened second substrate surface 85.

[0050] Roughening of the second substrate surface 85 in the perpendicular direction with respect to the second surface 32 provides the scattering of IR radiation instead of direct reflection to the dark pixels. Thus, the quantity of photons 101 hitting dark pixels can be reduced by scattering the photons 104 away from the dark pixels. FIG. 5 illustrates experimental results showing reducing of image artifacts from bright halogen lamp (row banding) with a roughened second surface 85 of the substrate 30. FIG. 5A is an image taken wit...

Example

[0056] Reference is now made to FIG. 6, which schematically illustrates a fourth embodiment of the solid-state imager 20 of the present invention. As set forth above with reference to FIGS. 2-4, the illustrated embodiment comprises an imaging device having a micro-lens array 70 formed over a color filter layer 100 and spacer layer 25, which are formed over a pixel cell array 26 formed in and / or over a first surface of substrate 30. The imager 20 further comprises at least one shaped grating 86 formed on a second surface of the substrate 30. FIG. 6 illustrates several shaped gratings 86. The shaped gratings 86 are preferably aligned at an angle β to a second surface 32 of the substrate 30. The shaped gratings 86 reduce the amount of IR photons accumulating in the dark pixels by the angles and orientation of the shaped gratings which are selected to reflect the photons away from the dark pixels.

[0057] The shaped gratings 86 can be formed by any chemical or mechanical methods know in ...

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Abstract

Imaging devices having reduced image artifacts are disclosed. The image artifacts in the imaging devices are reduced by redirecting, absorbing or scattering IR radiation that passes through the imaging device substrate away from dark pixels.

Description

BACKGROUND OF THE INVENTION [0001] The semiconductor industry currently uses different types of semiconductor-based imagers, such as charge coupled devices (CCDs), complementary metal oxide semiconductor (CMOS) devices, photodiode arrays, charge injection devices and hybrid focal plane arrays, among others. [0002] Solid-state image sensors, also known as imagers, were developed in the late 1960s and early 1970s primarily for television image acquisition, transmission, and display. An imager absorbs incident radiation of a particular wavelength (such as optical photons, x-rays, or the like) and generates an electrical signal corresponding to the absorbed radiation. There are a number of different types of semiconductor-based imagers, including CCDs, photodiode arrays, charge injection devices (CIDs), hybrid focal plane arrays, and CMOS imagers. Current applications of solid-state imagers include cameras, scanners, machine vision systems, vehicle navigation systems, video telephones, ...

Claims

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Application Information

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IPC IPC(8): H01L21/00
CPCH01L27/14603H01L27/14609H01L27/1462H01L31/0232H01L27/14625H01L27/14685H01L27/14623H01L27/146H01L31/0236
Inventor AGRANOV, GENNADIY A.KARASEV, IGOR
Owner APTINA IMAGING CORP
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